Hybrid laser scanning and imaging reader

ABSTRACT

An imaging module is supported by a housing of a reader for electro-optically reading indicia. The imaging module includes a solid-state imager having an array of image sensors for capturing return light from the indicia during reading. A laser scanning module is also supported by the housing and includes a scanner for scanning at least one of a laser beam from a laser and a field of view of a light detector in a scan pattern across the indicia during reading. A controller is operatively connected to the modules, and is operative for preventing reading interference between the modules during reading.

DESCRIPTION OF THE RELATED ART

Moving laser beam-based readers, in both handheld and hands-free modesof operation, have been used to electro-optically read coded symbols,particularly one-dimensional Universal Product Code (UPC) type symbols,in supermarkets, warehouse clubs, department stores, and other kinds ofretailers for many years. A laser generates a laser beam directed to asymbol associated with a product for reflection and scattering from thesymbol. A detector having a field of view detects light of variableintensity returning from the symbol. A scanner scans at least one of thelaser beam and the field of view in a scan pattern comprised of one ormore scan lines. When at least one of the scan lines sweeps over thesymbol, an electrical signal indicative of the intensity of the detectedreturn light is processed by signal processing circuitry including amicroprocessor; the symbol is read; and the product is identified.

Imager-based readers, in both handheld and hands-free modes ofoperation, have also been used to electro-optically read targets such ascoded symbols, particularly two-dimensional symbols, by employingsolid-state imagers to capture an image of each symbol. The imagercomprises an array of cells or photosensors, which correspond to imageelements or pixels in a field of view of the imager. Such an array maybe comprised of a one- or two-dimensional charge coupled device (CCD) ora complementary metal oxide semiconductor (CMOS) device, analogous tothose devices used in a digital camera to capture images.

The imager-based reader further typically includes an illuminator toilluminate the symbol during its reading with illumination light emittedfrom an illumination light source and directed to the symbol forreflection therefrom. The illumination light source may be locatedwithin and/or externally of the reader, and comprises one or more lightemitting diodes (LEDs). The imager-based reader yet further includeselectronic circuitry for producing electrical signals indicative of thelight captured by the array, and a microprocessor for processing theelectrical signals to produce each captured image.

It is therefore known to use a solid-state imager for capturing amonochrome image of a symbol as, for example, disclosed in U.S. Pat. No.5,703,349. It is also known to use a solid-state imager with multipleburied channels for capturing a full color image of a target as, forexample, disclosed in U.S. Pat. No. 4,613,895. It is common to provide atwo-dimensional CCD with a 640×480 resolution commonly found in VGAmonitors, although other resolution sizes are possible.

In the hands-free mode of either the moving laser beam-based reader orthe imager-based reader, an operator may slide or swipe the productbearing the symbol past a window of either reader, either from right toleft, or from left to right, in a “swipe” mode. Alternatively, theoperator may present the symbol on the product to an approximate centralregion of the respective window in a “presentation” mode. The choicedepends on operator preference or on the layout of a workstation inwhich the reader is used.

In the handheld mode of either the moving laser beam-based reader or theimager-based reader, the operator holds the respective reader in his orher hand during reading and aims the reader at the symbol to be read.The operator may first lift the reader from a countertop or a supportcradle. Once reading is completed, the operator may return the reader tothe countertop or to the support cradle.

Although the moving laser beam-based reader and the imager-based readerare generally satisfactory for their intended purposes, theircapabilities are limited in certain respects. The moving laserbeam-based reader works well in the handheld mode when readingone-dimensional symbols, but does not read certain two-dimensionalsymbols as well as the imager-based reader can, and cannot read othertwo-dimensional symbols at all. Sometimes, the moving laser beam-basedreader is too big and bulky to pick up and aim at a symbol easily. Theimager-based reader, on the other hand, works well in the hands-freemode for reading one- and two-dimensional symbols, but it works poorlyin the handheld mode primarily due to its housing design, which failsergonomically in several ways.

Specifically, a housing of a known imager-based reader is designed to begripped between an operator's thumb, on one side of the housing, and theoperator's fingertips on the other side of the housing, when picked upfor handheld reading. This is an uncomfortable grip. Also, reading ofthe known imager-based reader is initiated by pressing one of twoswitches on a side of the housing. The operator is required to press oneof the switches before aiming the reader at a symbol, and to release thebutton to initiate image capture. When the button is pressed, an aimingspot of light is projected on the symbol to facilitate aiming. When theaiming spot is on the symbol, the switch is released, and the readerdecodes and reads the symbol. The aiming spot turns off when the switchis released. If the switch is not pressed before aiming the reader at asymbol, the reader will scan the symbol automatically; however, thisleaves open the possibility of accidentally reading the wrong symbol asthe reader is moved towards the desired symbol to be read. Accidentalreads waste time and open the possibility of erroneously chargingcustomers at point-of-sale workstations, or of inaccurately recordingscanned inventory information, etc.

Another problem with the known imager-based readers is that the aimingspot only indicates where a center of the imager's field of view is. Itdoes not give any visual indication of where the edges of the field ofview are. This is a significant handicap when reading wide symbols, andparticularly when reading the two-dimensional symbols on the back ofdriver's licenses in most states of the United States. To read easily,these two-dimensional symbols must be positioned close to the readerwhere the field of view of the imager extends only slightly beyond theends of the symbol. If the symbol is held further away, the imager doesnot have adequate resolution to read some symbols and, if the symbol isheld closer, then the field of view will not cover the entire symbol,thereby rendering the symbol unreadable. The known imager-based readerprovides no visual guidance to the operator that helps the operatordetermine at what distance to hold the symbol. Hence, the operatortypically ends up waving the symbol around until the right distance isfinally found, at which time the reader beeps to indicate that thesymbol has been decoded. This is a slow process and not acceptable forbusy scanning environments.

Another problem that the known imager-based reader fails to address isthat, when used in the hands-free mode, the reader needs to have asomewhat limited working range (around six to eight inches), or thereader will accidentally scan products that customers place on thecounter-top nearby. However, when used in the handheld mode, the readeris better off with a greater working range, which makes it easier toscan symbols on products that are too big, heavy, or bulky to move closeup to the reader.

SUMMARY OF THE INVENTION

One feature of the present invention resides, briefly stated, in areader for, and a method of, electro-optically reading indicia,especially one- and/or two-dimensional symbols. Each symbol includeselements of different light reflectivity, e.g., bars and spaces. Thereader could be configured, in one embodiment, as a hands-free and/or ahand-held housing having a window. The housing may have a handle forhandheld operation and/or a base for supporting the housing on a supportsurface for hands-free operation. Preferably, the base is connected tothe housing in both the handheld and hands-free modes by being pivotablyconnected to the handle. Also, the housing is preferably configured witha gun-shaped configuration, and a manually actuatable trigger isprovided on the housing at a location underlying an operator'sforefinger when the operator holds the handle in the operator's hand. Inanother embodiment, the reader could be configured as a stationarybi-optic housing having dual windows.

In some applications, each window could be omitted, in which event, thereader has a windowless opening at which the indicia are located forreading. As used herein, the term “presentation area” is intended tocover both a window and a windowless opening. In the case of thehands-free reader, the symbol is swiped past, or presented to, thepresentation area and, in the case of the handheld reader, the readeritself is moved and the presentation area is aimed at the symbol. In thepreferred embodiments, the reader is installed in a retailestablishment, such as a supermarket, especially in a crampedenvironment.

An imaging module is supported by the housing, and includes a one- ortwo-dimensional, solid-state imager mounted in the reader. The imagerhas an array of image sensors operative, together with a focusing lensassembly, for capturing light from a one- or two-dimensional symbol ortarget through the presentation area during the reading to produce acaptured image. Preferably, the array is a CCD or a CMOS array. When thereader is operated in low light or dark ambient environments, theimaging module includes an illuminator for illuminating the symbolduring the reading with illumination light directed from an illuminationlight source through the presentation area. The illumination lightsource comprises one or more light emitting diodes (LEDs).

A laser scanning module is also supported by the housing and includes ascanner for scanning at least one of a laser beam from a laser and afield of view of a light detector in a scan pattern, typically comprisedof one or more scan lines, across the indicia during reading. The laserscanning module may also include signal processing circuitry forprocessing an electrical analog signal generated by the light detector,and a digitizer for converting the analog signal to a digital signal forsubsequent decoding.

In accordance with one aspect of this invention, a controller,especially but not necessarily operative for decoding the digitalsignal, is operatively connected to the modules, for preventing readinginterference between the modules during reading. For example, a modesensor is employed for detecting the mode of operation; and thecontroller enables the laser scanning module to read the indicia whenthe mode sensor detects the handheld mode, and enables the imagingmodule to read the indicia when the mode sensor detects the hands-freemode. The mode sensor is operative for detecting the mode of operationby sensing one of motion, position and orientation of the housing.

As another example, the controller enables the imaging module to capturethe return light during an exposure time of a frame, and downloads datagenerated by the imager during a read-out time of the frame; and thecontroller enables the laser scanning module to scan the indicia duringthe read-out time to prevent reading interference with the imagingmodule.

As still another example, the controller energizes the illuminator forilluminating the indicia during reading with the illumination lightdirected from the illuminating light source during the exposure time,and the controller disables the illuminating light source during theread-out time to prevent reading interference between the modules.

As yet another example, the illumination light and the laser beam havedifferent frequencies to prevent reading interference between themodules.

Additionally, the controller advantageously turns the laser beam offduring scanning, for example, at the end regions of the scan lines; andthe controller enables the imaging module to capture the return lightwhen the laser beam is turned off, again to prevent reading interferencewith the laser scanning module.

The housing may be configured to block the laser beam during scanning,for example, at the end regions of the scan lines. In that case, thecontroller enables the imaging module to capture the return light whenthe laser beam is blocked to prevent reading interference with the laserscanning module.

Another example resides in operating the scanner to sweep through a scanangle larger than a field of view of the imager. The controller enablesthe imaging module to capture the return light when the laser beam isoutside the field of view of the imager to prevent reading interferencebetween the modules.

In accordance with another aspect of the invention, the controller isoperative for distinguishing between types of the indicia, e.g., one- ortwo-dimensional symbols, and for enabling one of the modules to read theindicia of one determined type, and for enabling another of the modulesto read the indicia of another determined type. For example, the laserscanning module is especially good at reading one-dimensional symbols,and the imaging module is especially good at reading two-dimensionalsymbols.

In accordance with still another aspect of the invention, the controlleris operative for distinguishing between working distances at which theindicia are located relative to the reader, and for enabling one of themodules to read the indicia at working distances close to the reader,and for enabling another of the modules to read the indicia at workingdistances further from the reader. For example, the laser scanningmodule is especially good at reading symbols that are further away fromthe reader due to its large depth of field, and the imaging module isespecially good at reading symbols that are closer to the reader due toits smaller depth of field. This increases the range of the reader.

In accordance with yet another aspect of the invention, the controlleris operative for enabling the laser scanning module to scan the laserbeam over the indicia prior to reading to facilitate aiming of thereader at the indicia, and for enabling one of the modules to read theindicia after aiming. In other words, the laser scanning module not onlyperforms its reading function, but also assists the imaging module byperforming an aiming function. The scan pattern is visible on thesymbol.

A secondary aiming light projector may be employed in the imaging moduleto project a pattern of light that visibly indicates to the operatorwhere the periphery of the field of view of the imager is. For example,the aiming light projector might project an aiming pattern of lightshaped like a cross, which consists of a vertical line that matches thevertical dimensions of the field of view, and also a horizontal linewhose ends match the horizontal width of the field of view. Thisprojected aiming pattern should grow at the same angular rate as thescan pattern so that it properly indicates the extent of the field ofview at any distance from the reader. This aiming light pattern can becreated using either LED light or laser light. The aiming lightprojector makes it easy to scan difficult to read driver's licenses byclearly indicating to the operator where the periphery of the field ofview of the imager is, so as to facilitate fitting the driver's licensesymbol entirely within the field of view.

In the preferred embodiment, a horizontal line of the aiming pattern canbe created by a scanned laser line projected from the laser scanningmodule. The scan angle of the scanned laser beam is adjusted to matchthe divergence angle of the field of view of the imager so that the endsof the visible scan line is a visible indication of the ends of theimager's field of view. The operator can now use the laser scan line asa guide to properly position a symbol in front of the imager, forsubsequent decoding. The symbol can also be decoded by the laserscanning module if both modules are enabled to read at the same time. Insome cases, the operator may need to be able to selectively read asymbol that is positioned close to other symbols, for example, in abarcode menu list. The scan angle of the laser scanning module isadjustable to be reduced to a short line to facilitate aiming in theseapplications.

The invention still further resides in a method of electro-opticallyreading indicia, by supporting an imaging module by a housing, andcapturing return light from the indicia by the imaging module duringreading with a solid-state imager having an array of image sensors; bysupporting a laser scanning module by the housing, and scanning at leastone of a laser beam from a laser and a field of view of a light detectorin a scan pattern across the indicia by the laser scanning module duringreading; and by preventing reading interference between the modulesduring reading.

The reading interference is prevented in various ways. For example, theimaging module is enabled to capture the return light during an exposuretime of a frame, and data generated by the imager is downloaded during aread-out time of the frame. The laser scanning module is enabled to scanthe indicia during the read-out time to prevent reading interferencewith the imaging module. Also, the imaging module illuminates theindicia during reading with the illumination light during the exposuretime, and the illuminating light is disabled during the read-out time toprevent reading interference between the modules. The illumination lightand the laser beam are advantageously selected to have differentfrequencies to prevent reading interference between the modules. Thelaser beam is turned off during scanning; and the return light iscaptured when the laser beam is turned off, again to prevent readinginterference with the laser scanning module. The laser beam is blockedduring scanning; and the return light is captured when the laser beam isblocked to prevent reading interference with the laser scanning module.The laser beam is swept through a scan angle larger than a field of viewof the imager, and the return light is captured when the laser beam isoutside the field of view of the imager to prevent reading interferencebetween the modules.

The invention yet further resides in a method of electro-opticallyreading indicia, comprising the steps of holding a housing by a handleheld by an operator in a handheld mode of operation, and supporting thehousing by a base on a support surface during a hands-free mode ofoperation; supporting an imaging module by the housing, and capturingreturn light from the indicia during reading with a solid-state imagerhaving an array of image sensors; supporting a laser scanning module bythe housing, and scanning at least one of a laser beam from a laser anda field of view of a light detector in a scan pattern across the indiciaduring reading; detecting the mode of operation; and enabling the laserscanning module to read the indicia when the handheld mode is detected,and enabling the imaging module to read the indicia when the hands-freemode is detected.

The invention additionally resides in a method of electro-opticallyreading indicia, comprising the steps of: supporting an imaging moduleby a housing, and capturing return light from the indicia during readingwith a solid-state imager having an array of image sensors; supporting alaser scanning module by the housing, and scanning at least one of alaser beam from a laser and a field of view of a light detector in ascan pattern across the indicia during reading; and distinguishingbetween types of the indicia, and enabling one of the modules to readthe indicia of one determined type, and enabling another of the modulesto read the indicia of another determined type.

The invention also resides in a method of electro-optically readingindicia located in a range of working distances from the reader,comprising the steps of: supporting an imaging module by a housing, andcapturing return light from the indicia during reading with asolid-state imager having an array of image sensors; supporting a laserscanning module by the housing, and scanning at least one of a laserbeam from a laser and a field of view of a light detector in a scanpattern across the indicia during reading; and distinguishing betweenthe working distances of the indicia, and enabling one of the modules toread the indicia at working distances close to the reader, and enablinganother of the modules to read the indicia at working distances furtherfrom the reader.

The invention additionally resides in a method of electro-opticallyreading indicia, comprising the steps of: supporting an imaging moduleby a housing, and capturing return light from the indicia with asolid-state imager having an array of image sensor; supporting a laserscanning module by the housing, and scanning a laser beam in a visiblescan pattern across the indicia; and enabling the laser scanning moduleto scan the laser beam over the indicia prior to reading to facilitateaiming of the reader at the indicia, and enabling one of the modules toread the indicia after aiming.

Hence, this invention proposes a hybrid, dual module, reader that can beused as a presentation or swipe reader for hands-free reading of one- ortwo-dimensional symbols, and also offers excellent and intuitive“aim-and-shoot” ergonomics for handheld reading of one- ortwo-dimensional symbols by providing a gun-shaped housing having atrigger to be depressed by the operator's forefinger. The reader gives aclear visual indication of the extent of its field of view, tofacilitate reading of wide targets like driver's licenses andtwo-dimensional symbols in either the hands-free or handheld mode. Inaddition, the working distance range increases in the handheld mode ascompared to the hands-free mode.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an electro-optical reader operative ineither a hand-held mode, or a hands-free mode, for reading indicia inaccordance with this invention;

FIG. 2 is a broken-away, sectional view of the reader of FIG. 1schematically depicting various components therein;

FIG. 3 is a perspective view of a bi-optical reader operative forreading indicia in accordance with this invention;

FIG. 4 is a broken-away, sectional view of the reader of FIG. 3schematically depicting various components therein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference numeral 40 in FIG. 1 generally identifies an electro-optical,portable reader having a gun-shaped housing 42 connected to a base 44.The base 44 rests on a countertop or analogous support surface andserves for supporting the reader 40. The reader 40 can thus be used in ahands-free mode as a stationary workstation in which products bearingindicia, such as one- or two-dimensional symbols, are presented to, orslid or swiped past, a presentation area or window 46. The gun-shapedhousing 42 also has a handle that can be picked up by an operator offthe countertop and held in the operator's hand in a handheld mode. Atrigger 48 is located on the gun-shaped housing 42 at a locationunderlying an operator's forefinger when the operator holds the handlein the operator's hand in the handheld mode. The trigger 48 is manuallydepressed to initiate reading of the symbol. The handle is permanentlyand pivotably connected to the base 44 in both the handheld andhands-free modes for pivoting movement about a generally horizontalpivot axis that is generally parallel to, and elevated above, thecountertop. The housing is adjustably tiltable forward and back aboutthe pivot axis in the hands-free mode to aim the window 46 at the symbolto be read.

An imaging module 50 is supported by the housing 42, and includes a one-or two-dimensional, solid-state imager 30 mounted in the reader. Theimager 30 has an array of image sensors operative, together with afocusing lens assembly 31, for capturing light from a one- ortwo-dimensional symbol or target through the presentation area 46 duringthe reading to produce an electrical signal indicative of a capturedimage for subsequent decoding. Preferably, the array is a CCD or a CMOSarray. When the reader 40 is operated in low light or dark ambientenvironments, the imaging module 50 includes an illuminator 32 forilluminating the symbol during the reading with illumination lightdirected from an illumination light source through the presentation area46. The illumination light source comprises one or more light emittingdiodes (LEDs). An aiming light generator 34 may also be provided forprojecting an aiming light pattern or mark on the symbol prior toreading.

In operation of the imaging module 50, a controller 70, as describedbelow, sends a command signal to pulse the illuminator LEDs 32 for ashort time period, say 500 microseconds or less, and energizes theimager 40 during an exposure time period of a frame to collect lightfrom a target symbol during said time period. A typical array needsabout 33 milliseconds to read the entire target image and operates at aframe rate of about 30 frames per second. The array may have on theorder of one million addressable image sensors.

A laser scanning module 60 is also supported by the housing 42 andincludes a scanner 62 for scanning at least one of a laser beam from alaser 64 and a field of view of a light detector 66 in a scan pattern,typically comprised of one or more scan lines, across the indicia duringreading. The laser scanning module 60 may also include optics 61 forfocusing the laser beam to have a large depth of field, and a digitizer68 for converting an electrical analog signal generated by the detector66 into a digital signal for subsequent decoding,

In operation of the laser scanning module 60, the controller 70, asdescribed below, energizes the laser to emit the laser beam, andenergizes the scanner to sweep the laser beam in the scan pattern. Thecontroller 70 also processes the digitized signal from the digitizer 68.

In accordance with one aspect of this invention, a programmedmicroprocessor or controller 70, especially but not necessarilyoperative for decoding the digital signal from the digitizer 68 or theelectrical signal indicative of the captured image from the imager 30,is operatively connected to the modules 50, 60 for preventing readinginterference between the modules during reading. For example, a modesensor 72 is employed for detecting the mode of operation; and thecontroller 70 enables the laser scanning module 60 to read the indiciawhen the mode sensor 72 detects the handheld mode, and enables theimaging module 50 to read the indicia when the mode sensor 72 detectsthe hands-free mode. The mode sensor 72 is operative for detecting themode of operation by sensing one of motion, position and orientation ofthe housing 42. For example, the mode sensor 72 can detect when thereader 40 is lifted by means of a switch mounted on an underside of thebase 44, the switch being pushed in when the reader is on a supportsurface, and the switch being released and moved outwards when thereader 40 is lifted. The mode sensor 72 can also be an orientationsensor or tilt switch for detecting whether or not the reader is in apredetermined orientation. The mode sensor 72 can also be anaccelerometer for detecting motion when the reader is lifted, or lack ofmotion when the reader is on the support surface, thereby causing thereader to automatically switch between modes.

As another example of preventing reader interference, the controller 70enables the imaging module 50 to capture the return light during anexposure time of a frame, and downloads data generated by the imager 30during a read-out time of the frame; and the controller 70 enables thelaser scanning module 60 to scan the indicia during the read-out time toprevent reading interference with the imaging module 50.

As still another example, the controller 70 energizes the illuminator 32for illuminating the indicia during reading with the illumination lightdirected from the illuminating light source during the exposure time,and the controller 70 disables the illuminating light source during theread-out time to prevent reading interference between the modules 50,60.

As yet another example, the illumination light and the laser beam havedifferent frequencies to prevent reading interference between themodules 50, 60.

Additionally, the controller 70 advantageously turns the laser beam offduring scanning, for example, at the end regions of the scan lines; andthe controller 70 enables the imaging module 50 to capture the returnlight when the laser beam is turned off, again to prevent readinginterference with the laser scanning module 60.

The housing 42 may be configured to block the laser beam duringscanning, for example, at the end regions of the scan lines. In thatcase, the controller 70 enables the imaging module 50 to capture thereturn light when the laser beam is blocked to prevent readinginterference with the laser scanning module 60.

Another example resides in operating the scanner 62 to sweep through ascan angle larger than a field of view of the imager 30. The controller70 enables the imaging module 50 to capture the return light when thelaser beam is outside the field of view of the imager 30 to preventreading interference between the modules 50, 60.

In accordance with another aspect of the invention, the controller 70 isoperative for distinguishing between types of the indicia, e.g., one- ortwo-dimensional symbols, and for enabling one of the modules to read theindicia of one determined type, and for enabling another of the modulesto read the indicia of another determined type. For example, the laserscanning module 60 is especially good at reading one-dimensionalsymbols, and the imaging module 50 is especially good at readingtwo-dimensional symbols.

In accordance with still another aspect of the invention, the controller70 is operative for distinguishing between working distances at whichthe indicia are located relative to the reader 40, and for enabling oneof the modules to read the indicia at working distances close to thereader, and for enabling another of the modules to read the indicia atworking distances further from the reader. For example, the laserscanning module 60 is especially good at reading symbols that arefurther away from the reader 40 due to its large depth of field, and theimaging module 50 is especially good at reading symbols that are closerto the reader due to its smaller depth of field. This increases therange of the reader.

In accordance with yet another aspect of the invention, the controller70 is operative for enabling the laser scanning module 60 to scan thelaser beam over the indicia prior to reading to facilitate aiming of thereader 40 at the indicia, and for enabling one of the modules to readthe indicia after aiming. In other words, the laser scanning module 60not only performs its reading function, but also assists the imagingmodule 50 by performing an aiming function. The scan pattern is visibleon the symbol.

FIG. 3 depicts a dual window, bi-optic, point-of-transaction workstationor housing 10 used by retailers to process transactions involving thepurchase of products bearing an identifying symbol, typically the UPCsymbol described above. Housing 10 has a generally horizontal window 12set flush into a countertop 14, and an upright window 16 set flush, orrecessed, into a raised housing portion 18 above the countertop 14. Anoperator 24 is shown holding a product 26 bearing a symbol 28.

As shown in FIG. 4, the imaging module 50 including the imager 30 andthe illuminator 32 is mounted in the bi-optic housing 10. The laserscanning module 60 is also mounted in the bi-optic housing 10. Themodules 50, 60 could be dedicated to individual windows as illustrated,or could share one or both of the windows 12, 16. The modules 50, 60 areoperatively connected to the controller 70 operative, as describedabove, for controlling the operation of these modules. Preferably, thecontroller 70 is the same as the one used for decoding light scatteredfrom the indicia and for processing and analyzing the captured targetimages.

Reading interference between the integrated laser scanning and imagingmodules is prevented in various ways. For example, the imager 30 mayhave a short exposure time in a frame that is typically about 25% orless of the frame read-out time. In the next generation pico-imager inwhich a sixty frames per second frame rate is employed, the frameread-out time is a minimum of about 16.67 ms and the exposure time isabout 4 ms. Since this imager 30 has a global electronic shutter, returnlight is only captured during the exposure time. Therefore, when theimager 30 is reading out data but not exposing, the laser scanningmodule 60 can operate without interfering with the imager moduleoperation. Also, the imager illuminator 32 is not switched on duringthis time, so it does not interfere with the operation of the laserscanning module 60. The laser scanning module 60 can operate at a dutycycle of at least about 75% and therefore there is very little impact onthe reader performance. If the exposure time of the imager 30 is shortenough, the two modules appear to operate concurrently. If the exposuretime is made very short (tenths of a millisecond), the operation of thereader is practically not interrupted.

Another approach for multiplexing the laser scanning and imaging modulesis to use different wavelengths for the laser beam and the illuminationlight, and to use optical filters in the collection optics of eachmodule to collect only the light dedicated for each module. For example,the illumination light could use a deeper red, blue, green or nearinfrared source, while the laser beam could use a different red source.

Another approach would be to let the laser scanning module continueoperating, but ignore the pixels in the two-dimensional image capturedby the imaging module that are exposed to the laser light.

Some laser scanning modules turn off the laser 64 near end regions ofeach scan line, where the scanner 62 slows down and reverses direction.If such a laser scanning module is used in conjunction with an imagingmodule, then the modules can be synchronized so that the illuminator 32and the exposure time of the imager 30 is activated during thislaser-off time period when the laser scanning module is not capturingsymbol data. This synchronization enables the two modules to operatewithout interfering with each other at all. If the laser scanning moduleprovides an output start-of-scan (SOS) signal which indicates when thescanner is at an end region of each scan line, then this SOS signal canbe used to synchronize the modules.

Many laser scanning modules employ an automatic gain control (AGC)circuit whose behavior could be corrupted by the bright flash of theilluminator LEDs 32 used by the imaging module. This could degrade theperformance of the laser scanning module. This problem can be eliminatedby disabling the AGC whenever the LEDs 42 are flashed.

Some laser scanning modules do not turn off the laser 64 at the endregions of each scan line. Even when this kind of laser scanning moduleis used, it is still advantageous to synchronize the imaging module withthe SOS signal so as to flash the LEDs 32 and capture an image only whenthe laser beam is at or near one end region of the scan line, since thelaser does not scan well where the laser beam slows down beforereversing direction. The housing of the reader can be designed to blockthe end region of each scan line where the laser beam will be during theLEDs 32 flash, so that operators do not attempt to place a symbol at theend of the scan line where the reader may not read.

Another approach would be to design the laser scanning and imagingmodules such that the scan angle of the scanning laser beam is largerthan the field of view of the imager 30. The imager 30 can besynchronized to expose the image when the laser beam is outside of thefield of view of the imager 30, thereby eliminating the interferencebetween the modules. Similar to the description above, the AGC of thelaser scanning module can be disabled during the illuminator 32 flash toeliminate the interference between the modules.

As mentioned above, the LEDs 32 illuminate any symbol or object placedin front of the reader. The secondary aiming light projector 34 projectsa pattern of light that visibly indicates to the operator 24 where theperiphery of the field of view of the imager 30 is. For example, theaiming light projector 34 might project an aiming pattern of lightshaped like a cross, which consists of a vertical line that matches thevertical dimensions of the field of view, and also a horizontal linewhose ends match the horizontal width of the field of view. Thisprojected aiming pattern should grow at the same angular rate as thescan pattern so that it properly indicates the extent of the field ofview at any distance from the reader. This aiming light pattern can becreated using either LED light or laser light. The aiming lightprojector 34 makes it easy to scan difficult to read driver's licensesby clearly indicating to the operator where the periphery of the fieldof view of the imager 30 is, so as to facilitate fitting the driver'slicense symbol entirely within the field of view.

In the preferred embodiment, a horizontal line of the aiming pattern canbe created by a scanned laser line projected from the laser scanningmodule 60. The scan angle of the scanned laser beam is adjusted to matchthe divergence angle of the field of view of the imager 30 so that theends of the visible scan line is a visible indication of the ends of theimager's field of view. The operator can now use the laser scan line asa guide to properly position a symbol in front of the imager 30, forsubsequent decoding. The symbol can also be decoded by the laserscanning module if both modules are enabled to read at the same time. Insome cases, the operator may need to be able to selectively read asymbol that is positioned close to other symbols, for example, in abarcode menu list. The scan angle of the laser scanning module isadjustable to be reduced to a short line to facilitate aiming in theseapplications.

In the hands-free mode, the imaging module becomes the primary readingmodule. An aiming pattern is not needed when scanning one-dimensionalsymbols, which is the most common application for this kind of reader,so that the laser 64 can be turned off most of the time. If atwo-dimensional symbol is detected in front of the reader, then thelaser 64 can be turned on to help the operator align the two-dimensionalsymbol to the field of view. After the two-dimensional symbol has beendecoded, the laser 64 will turn off automatically until the nexttwo-dimensional symbol is detected by the imager. Hence, the imager 30is the primary means of decoding symbols when in the hands-free mode,and the laser 64 is used as an aiming guide. The secondary aimingprojector 34 other than the scanning laser 64 can be used to augment asingle scan line generated by the laser scanning module.

In the handheld mode, the laser scanning module becomes the primaryreading module, and one-dimensional symbols represent the majority ofsymbols to be read. Occasionally, the operator may want to read atwo-dimensional symbol, such as printed on a driver's license. Theoperator can aim the reader at the two-dimensional symbol, and the laserscanning module can recognize that it is looking at a two-dimensionalsymbol by the unique start/stop characters of the two-dimensionalsymbol, or by the structure of the internal characters. When thishappens, the imaging module will be enabled to read the two-dimensionalsymbol, while the laser scan line may continue to be used to aim thereader to position the two-dimensional symbol within the field of viewof the imager, as described above.

In some cases, it might be desirable to have both modules active at thesame time. For example, in the handheld mode, the laser scanning modulewill provide an extra range of working distances, which is useful whenreading one-dimensional symbols at a distance, but the imager could beused to read one-dimensional symbols omnidirectionally closer to thereader. The reader can therefore be user-programmable to have either thelaser scanning module, or the imaging module, or both operational at thesame time, or exclusively, in either the hands-free or handheld mode, orto have one module enable the other module, when necessary, as describedabove. User-programmability can be via scanning special command symbolswith either reader, or by communication with a host.

An alternative embodiment would be to use a linear imager in place ofthe laser scanning module. In this case, the linear illumination line ofthe linear imager would take the place of the laser scan line foraiming. Switching between the linear imager and area imager would beaccomplished in the same ways, as described above.

Another way to achieve similar results would be to use the area imagerto simulate a single line scanner when in handheld mode. This can beaccomplished by projecting a horizontal line of LED light near thecenter of the field of view of the area imager, and only using a centralline or several central lines of the area imager to decode with. Thiseliminates the need for a secondary optical system for a linear imageror laser scanner, but does not provide the added range of a laser orlinear imager when in handheld mode.

This invention enables, for the first time, a reader that providesexcellent scanning ergonomics in both hands-free and handheld modes, andalso provides optimum reading performance in both modes. The scan angleof the laser scanning module is advantageously matched to the field ofview angle of the imager. Switching between the modules depends on themode being used, what kind of symbology is being read, the workingdistance to the symbol, or by being user-programmed to enable whichevermodule is needed in either the handheld or hands-free mode.

Another improvement in the alternate modes of hands-free scanning vs.“point and shoot” handheld scanning is to have longer exposure timegoals for the handheld mode. In the hands-free mode, a short exposuretime allows good tolerance of motion in the presented symbol, and alsolimits the working distance range by limiting the amount ofillumination. In the handheld mode, the reader can have a longerexposure as the symbol is not being swiped, thereby allowing forsignificantly more working range.

It will be understood that each of the elements described above, or twoor more together, also may find a useful application in other types ofconstructions differing from the types described above. Thus, readershaving different configurations can be used.

While the invention has been illustrated and described as integrating alaser scanning module and an imaging module in a hybrid reader andmethod, it is not intended to be limited to the details shown, sincevarious modifications and structural changes may be made withoutdeparting in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

1-22. (canceled)
 23. A reader for electro-optically reading indicia,comprising: a housing; an imaging module supported by the housing andincluding a solid-state imager having an array of image sensors forcapturing return light from the indicia during reading; a laser scanningmodule supported by the housing and including a scanner for scanning atleast one of a laser beam from a laser and a field of view of a lightdetector in a scan pattern across the indicia during reading; and acontroller operatively connected to the modules, for distinguishingbetween types of the indicia, and for enabling one of the modules toread the indicia of one determined type, and for enabling another of themodules to read the indicia of another determined type.
 24. A reader forelectro-optically reading indicia located in a range of workingdistances from the reader, comprising: a housing; an imaging modulesupported by the housing and including a solid-state imager having anarray of image sensors for capturing return light from the indiciaduring reading; a laser scanning module supported by the housing andincluding a scanner for scanning at least one of a laser beam from alaser and a field of view of a light detector in a scan pattern acrossthe indicia during reading; and a controller operatively connected tothe modules, for distinguishing between the working distances of theindicia, and for enabling one of the modules to read the indicia atworking distances close to the reader, and for enabling another of themodules to read the indicia at working distances further from thereader.
 25. A reader for electro-optically reading indicia, comprising:a housing; an imaging module supported by the housing and including asolid-state imager having an array of image sensors for capturing returnlight from the indicia; a laser scanning module supported by the housingand including a scanner for scanning a laser beam in a visible scanpattern across the indicia; and a controller operatively connected tothe modules, for enabling the laser scanning module to scan the laserbeam over the indicia prior to reading to facilitate aiming of thereader at the indicia, and for enabling one of the modules to read theindicia after aiming. 26-47. (canceled)
 48. A method ofelectro-optically reading indicia, comprising the steps of supporting animaging module by a housing, and capturing return light from the indiciaduring reading with a solid-state imager having an array of imagesensors; supporting a laser scanning module by the housing, and scanningat least one of a laser beam from a laser and a field of view of a lightdetector in a scan pattern across the indicia during reading; anddistinguishing between types of the indicia, and enabling one of themodules to read the indicia of one determined type, and enabling anotherof the modules to read the indicia of another determined type.
 49. Amethod of electro-optically reading indicia located in a range ofworking distances from the reader, comprising the steps of supporting animaging module by a housing, and capturing return light from the indiciaduring reading with a solid-state imager having an array of imagesensors; supporting a laser scanning module by the housing, and scanningat least one of a laser beam from a laser and a field of view of a lightdetector in a scan pattern across the indicia during reading; anddistinguishing between the working distances of the indicia, andenabling one of the modules to read the indicia at working distancesclose to the reader, and enabling another of the modules to read theindicia at working distances further from the reader.
 50. A method ofelectro-optically reading indicia, comprising the steps of: supportingan imaging module by a housing, and capturing return light from theindicia with a solid-state imager having an array of image sensor;supporting a laser scanning module by the housing, and scanning a laserbeam in a visible scan pattern across the indicia; and enabling thelaser scanning module to scan the laser beam over the indicia prior toreading to facilitate aiming of the reader at the indicia, and enablingone of the modules to read the indicia after aiming.
 51. The method ofclaim 50, and projecting an aiming pattern on the symbol which visiblyindicates an entire extent of a field of view of the imager.